An antenna is used as a radio transmitter to send out information via a radio wave that carries the intended information to be sent out or a radio receiver that receives an incoming radio wave to extract information. In transmission, a radio transmitter supplies an electric current oscillating at a radio frequency (e.g., a high frequency alternating current (AC)) to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of an electromagnetic wave to produce a voltage or current at its terminals that is processed in a receiver.